Method and apparatus for installing subsea insulation

ABSTRACT

Provided herein is a system and apparatus for installing subsea insulation on flowlines, connectors and equipment. This system provides a lightweight, thin mold designed and built to suit the parameters of the subsea item to be insulated. The mold fits and seals around the area to be insulated which is then injected with an insulation material by a remote operation vehicle (ROV). The insulation material is injected as a liquid solution that is a combination of an insulation solution and a catalyst solution mixed together during the injection process. The liquid solution is then allowed to solidify, forming a gel molded insulation.

BACKGROUND OF THE INVENTION

The present invention relates generally to a method and apparatus forinstalling insulation on subsea oil and gas flowlines, connectors andother equipment.

Subsea oil and gas wells are constantly exposed to cold seawater thatcan often times be just a few degrees above freezing. Subsea oilproduction often leaves the well at much higher temperatures, sometimesexceeding 300 degrees Fahrenheit. When the flow of oil is interruptedfor any reason, the production fluid in the flowline begins to cool. Ifthe production fluid was allowed to sufficiently cool, oil productioncould be completely stopped due to the formation of hydrates or paraffinblocks that can form in the flowline and connectors, inhibitingresumption of the flow of the fluid.

It is therefore desirable to insulate the subsea production flowlineconnectors to maintain the much hotter temperature of the oil and gasproduction. This is commonly done with rigid covers, commonly referredto as “dog houses” in the industry. These dog houses are placed aroundthe flowline connectors or other equipment to be insulated, and haveproven to do a less than adequate job of insulation. However, one keydisadvantage of using dog houses is that because they are rigid covers,seawater is able to flow through gaps between the cover and theinsulated flowline or equipment. This water flow allows heat to escape,thereby reducing the effectiveness of the insulation.

It would therefore be desirable to develop a system that can installinsulation on subsea flowline, connectors or equipment without reducingthe effectiveness of the insulation.

SUMMARY OF THE INVENTION

Provided herein is a system and apparatus for installing subseainsulation on subsea flowlines, connectors and equipment. This systemprovides a lightweight, thin mold designed and built to suit theparameters of the subsea item to be insulated. The mold fits and sealsaround the area to be insulated, and is then injected with an insulationmaterial by a remotely operated vehicle (ROV). The insulation materialis injected as a liquid solution, thereby avoiding the presence of gapsin the insulation. This liquid solution is a combination of aninsulation solution and a catalyst mixed together during the injectionprocess. The mixture is then allowed to solidify, forming the moldedinsulation.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

One embodiment of the present invention first uses a subsea gelinsulation mold. This mold is a pre-engineered fiberglass, plastic ormetal enclosure, the purpose of which is to fit around the subseaflowline, connector or other equipment to be insulated. Generally, themold will comprise a hinged enclosure that is closed and secured aroundthe item to be insulated. In one embodiment, the mold comprises gasketsto provide a tight seal between the mold and the item to be insulated.The mold can either be preinstalled on the flowline, connector or otherequipment to be insulated, or it can be installed by a remotely operatedvehicle (ROV). The process of installing the subsea gel insulation moldwith an ROV involves deploying the ROV to the site of the item to beinsulated, and using the ROV to install the mold. In one embodiment, themold is attached to the ROV itself, however if multiple molds areneeded, a separate mold deployment skid can be provided to supply themultiple molds.

Also provided is a subsea insulation solution reservoir skid, which isdeployed separately from the ROV in the vicinity of the subseainsulation installation site. The subsea insulation solution reservoirskid comprises a flexible insulation solution reservoir and a hose fordelivering the insulation solution.

One embodiment of the present invention involves the use of a subsea gelinjection system. This system is a remotely operated package integratedwithin the frame of the ROV, or provided as a separate skid mountedunder the ROV, depending upon the number of injection molds to be filledand the insulation solution/catalyst ratio provided. The subsea gelinjection system comprises a pump module, which itself comprisesseparate pumps for the insulation solution and the catalyst. The systemalso uses a mixing nozzle with an injection hose fitted with a singleport hot stab for mixing the insulation solution and catalyst uponinjection of the mixture into the mold installed around the subseaflowline, connector or equipment to be insulated. Finally, the systemcomprises a catalyst reservoir for containing the catalyst prior to itsinjection into the mold.

In one method of the present invention, the insulation solution ispumped into the flexible bladder on the subsea insulation solutionreservoir skid, and the catalyst is pumped into the catalyst reservoiron the subsea gel injection system skid. The pump module of the subseagel injection skid is connected to the ROV system so as to draw powerfrom the ROV system. For instance, if the pumps are hydraulic pumps,then they are connected to the ROV hydraulic system, however if thepumps are electric, then they would be connected to the ROV electricalsystem. The mixing nozzle is then connected to the pump module, and theinjection hose and hot stab are installed near the ROV manipulator. Themolds are either installed on the ROV skid or on the separate molddeployment skid, along with the mold installation tool.

The insulation solution reservoir and mold deployment skids are loweredfrom the water surface to the sea floor on separate surface deployedlift lines and placed near the work site. The ROV, such as, for example,the INNOVATOR® manufactured by Sonsub Inc. of Houston, Tex., is thenlaunched and lowered to the work site. The process of installing theinsulation can then begin.

First, the ROV flies to the mold deployment skid and uses itsmanipulator to connect a hydraulic hot stab to the mold installationtool. The ROV grab arm then picks up the mold installation tool andmaneuvers the installation tool over a mold on the mold deployment skid.The hydraulic hot stab powers the installation tool to grab the mold anddisconnect the mold from the skid. The ROV then flies the mold over tothe flowline, connector or other equipment to be insulated, where theinstallation tool locks the mold around the flowline, connector or otherequipment to be insulated.

The ROV then returns the installation tool to the mold deployment skid,after which the ROV flies to the insulation solution reservoir skid. TheROV pulls the hose on the insulation solution reservoir skid over to thearea of the mold, and then uses its manipulator to connect theinsulation solution reservoir hose hot stab to the gel pump. The ROVmanipulator then connects the mixing nozzle hose to the mold receptacle,and starts up the catalyst and insulation solution pumps to pump thecatalyst and insulation solution through the mixing nozzle and into themold. After the mold is filled with the insulation solution/catalystmixture, the catalyst pump is disengaged, and a small quantity ofinsulation solution is pumped through the mixing nozzle to clean out themixed solution, preventing insulation gel from curing and hardeningwithin the mixing nozzle. The ROV manipulator then disconnects theinjection hose, and is now ready to install the next mold. Once all themolds are installed, the ROV, mold skid, and insulation solutionreservoir skid are recovered to the surface.

Insulation gel for use in the present invention is known in the art. Onetype of the insulation gel described above, in which an insulationsolution is mixed with a catalyst upon injection into the mold, isDEEPGEL(TM) offered by Ythan Environmental Services Ltd. However, anytype of insulation that is injectable into a mold and allowed to cure orharden can be used in the present invention. Some such insulations maynot require the use of a catalyst for hardening the insulation, in whichcase there would be no need for a catalyst container or catalyst pump,thereby reducing the amount of equipment to perform the method and buildthe apparatus of the present invention.

While the apparatuses and methods of the present invention have beendescribed in terms of preferred embodiments, it will be apparent tothose of skill in the art that variations may be applied to what hasbeen described herein without departing from the concept and scope ofthe invention. All such similar substitutes and modifications apparentto those skilled in the art are deemed to be within the scope andconcept of the invention as it is set out in the following claims.

1. An apparatus for installing subsea insulation using a remotelyoperated vehicle comprising: a subsea gel insulation mold; a subseainsulation solution reservoir skid; and a subsea gel injection system.2. The apparatus of claim 1, wherein the subsea gel insulation mold isselected from the group consisting of a pre-engineered fiberglassenclosure, a plastic enclosure, and a metal enclosure.
 3. The apparatusof claim 1, wherein the subsea gel insulation mold is a hingedenclosure.
 4. The apparatus of claim 1, wherein the subsea gelinsulation mold comprises gaskets, wherein the gaskets provide a tightseal between the subsea gel insulation mold and an item to be insulated.5. The apparatus of claim 1, wherein the subsea gel insulation mold ispreinstalled on an item to be insulated.
 6. The apparatus of claim 1,wherein the subsea gel insulation mold is installed by the remotelyoperated vehicle.
 7. The apparatus of claim 1, further comprisingmultiple gel insulation molds, wherein a mold deployment skid suppliesthe multiple gel insulation molds.
 8. The apparatus of claim 1, whereinthe subsea insulation solution reservoir skid comprises a flexible gelreservoir for supplying insulation solution and a hose for deliveringthe insulation solution.
 9. The apparatus of claim 1, wherein the subseagel injection system is integrated within the frame of the remotelyoperated vehicle.
 10. The apparatus of claim 1, wherein the subsea gelinjection system is provided on a skid separate from the remotelyoperated vehicle.
 11. The apparatus of claim 10, wherein the subsea gelinjection system skid is mounted to the remotely operated vehicle. 12.The apparatus of claim 1, further comprising an insulation solutionpump.
 13. The apparatus of claim 1, further comprising a catalyst pump.14. The apparatus of claim 1, further comprising a mixing nozzle formixing insulation solution and catalyst.
 15. The apparatus of claim 1,further comprising a catalyst reservoir.
 16. A method for installingsubsea insulation comprising: installing a subsea gel insulation mold onan item to be insulated; and using a remotely operated vehicle tosimultaneously pump insulation solution and catalyst into the subsea gelinsulation mold.
 17. The method of claim 16, wherein the remotelyoperated vehicle installs the subsea gel insulation mold on the item tobe insulated.
 18. The method of claim 16, wherein the insulationsolution and catalyst are pumped into the subsea gel insulation moldthrough a mixing nozzle.
 19. The method of claim 16, wherein theinsulation solution and catalyst are pumped into the subsea gelinsulation mold using an insulation solution pump for pumping theinsulation solution and a catalyst pump for pumping the catalyst. 20.The method of claim 16, wherein the subsea gel insulation mold isselected from the group consisting of a pre-engineered fiberglassenclosure, a plastic enclosure, and a metal enclosure.
 21. The method ofclaim 16, wherein the subsea gel insulation mold is a hinged enclosure.22. The method of claim 16, wherein the subsea gel insulation moldcomprises gaskets, wherein the gaskets provide a tight seal between thesubsea gel insulation mold and the item to be insulated.
 23. The methodof claim 16, wherein the subsea gel insulation mold is installed by theremote operated vehicle.
 24. The method of claim 16, wherein the subseagel insulation molds are provided by a mold deployment skid.
 25. Themethod of claim 16, wherein the insulation solution is provided by asubsea insulation solution reservoir skid.
 26. The method of claim 16,wherein insulation solution and catalyst are pumped from a subsea gelinjection system.
 27. The method of claim 26, wherein the subsea gelinjection system is integrated within the frame of the remotely operatedvehicle.
 28. The method of claim 26, wherein the subsea gel injectionsystem is provided on skid separate from the remotely operated vehicle.29. The method of claim 28, wherein the subsea gel injection system skidis mounted to the remotely operated vehicle.
 30. A method for installingsubsea insulation comprising: using a remotely operated vehicle toinstall a subsea gel insulation mold to an item to be insulated; andusing a remotely operated vehicle to pump insulation solution into thesubsea gel insulation mold.
 31. The method of claim 30, wherein theremotely operated vehicle installs the subsea gel insulation mold to theitem to be insulated.
 32. The method of claim 30, wherein the subsea gelinsulation mold is selected from the group consisting of apre-engineered fiberglass enclosure, a plastic enclosure, and a metalenclosure.
 33. The method of claim 30, wherein the insulation solutionis provided by a subsea insulation solution reservoir skid.
 34. Anapparatus for installing subsea insulation using a remotely operatedvehicle comprising: a means for storing insulation solution; a means formolding insulation solution; and a means for injecting the storedinsulation solution into the molding means.